1. Technical Field
The present disclosure relates generally to a blow-molded article and, more particularly to a hinge group in the blow-molded article, and a method and a mold for forming the hinge group.
2. Description of Related Art
Blow molding is primarily used for producing hollow articles, and is carried out by inflating high-temperature plastic parison within a molding chamber. A number of blow-molded articles have a hinge group. An existing hinge group generally has several hinge arms being set up on two parts of a blow-molded article and stretching out towards hinge arms on opposite parts, which are normally classified as an upper hinge arm and a lower hinge arm. The hinge arms have shaft holes respectively and various portions of the hinge arms are alternately set up. When the two parts are joined together, corresponding hinge arms are connected with their shaft holes being on the same axis to form a common through hole. By allowing hinge pin to pass through this shaft hole, the two parts of the blow-molded article are joined together.
Generally, molding a shaft hole in a hinge arm using blow molding requires a very complex mold. In a molding process disclosed in U.S. Pat. No. 5,288,453A, a core rod is placed between male and female molds, with the core rod being matched with a shaft hole of a hinge arm to be molded. A parison is placed between the two molds which are then combined together with any excessive part of the parison being cut off. The parison is then inflated by blowing air thereunto, pressurized, and cooled down. The two molds are unloaded and the core rod is removed. As illustrated, a procedure of removing a core rod exists in the conventional blow molding when a shaft hole of a hinge arm is molded, thus making the procedure a relatively complicated one. Further, the wall of the shaft hole that has been shaped is prone to damages when the core rod is removed, thus leading to a low product acceptability rate.